Question

$∆U^Θ$ of combustion of methane is – $X\ kJ \ mol^{–1}$. The value of $∆H^Θ$ is

• A. $= ∆U^Θ$
• B. $>∆U^Θ$
• C. $<∆U^Θ$
• D. $=0$

Answer 1

Answer: (C)

$<∆U^Θ$

Answer 2

Since $∆H^Θ = ∆U^Θ + ∆n_gRT$ and $∆U^Θ = –X \ kJ \ mol^{–1}$,
$∆H^Θ = (–X) + ∆n_gRT$|
⇒ $∆H^Θ < ∆U^Θ$

Therefore, the correct option is (C): $< ∆U^Θ$